Is There a Future for Hypoallergenic Milk?

Is There a Future for Hypoallergenic Milk?

Posted on 10/11/2012 at 10:05:17 AM by Student Blogger

By Sylvia Ley

A recent publication by New Zealand researchers has gained media
attention. TIME published an article called, “Researchers
Genetically Modify a Cow to Produce Low-Allergy Milk” (1). The term
“low-allergy” milk attracted my attention enough to look for the
original paper published in The Proceedings of the National
Academy of Science (2).

About 2-3% of infants are allergic to cow's milk protein during the
first year of life. Cow's milk contains the protein called
beta-lactoglobulin (BLG). The BLG protein, which is not present in
human milk, is known to cause allergic reactions. Researchers led
by Dr. Goetz Laible from AgResearch reported that they have
genetically engineered a calf named Daisy who produces BLG-free
milk.

Before Daisy, Dr. Laible and colleagues tested the process in a
cheaper mouse model. Because a mouse does not naturally
express the BLG protein, a mouse was engineered to produce the
sheep BLG protein in mouse milk. Two microRNAs were then
introduced into the mouse to knock-down the expression of the BLG
protein employing a RNA interference technique. This resulted
in 96% reduction of the BLG protein in mouse milk. They then
produced a female transgenic calf engineered to express the same
two microRNAs targeting the BLG protein. The transgenic calf,
Daisy, was then hormonally induced to lactate. After assessed
by a number of different techniques (i.e. the Coomassie blue
staining, Western, and HPLC), Daisy's milk was determined to
contain no detectable BLG. Researchers also reported that the
milk had altered protein composition to compensate for missing BLG.
The whey-to-casein ratio in Daisy's milk was 4:96 compared to 21:79
in wild-type normal cow's milk.

The implication of such a drastic whey-to-casein ratio change will
need further investigations before human infant consumption. It
also raises other safety concerns including whether composition of
other bioactive components in milk was altered through the process.
Although the BLG protein was not detected in this paper, further
investigation is needed to confirm whether Daisy's milk is
hypoallergenic to human. Another question to consider is whether
this procedure will lead to cost-effective ways to supply
hypoallergenic milk. Will Daisy continue to produce BLG-free milk?
Can she live a healthy long lactating life? Also, this genetically
modified animal product will have to be approved by food safety
regulatory bodies before reaching consumers. After Daisy's
milk passes this long process, her milk will have to compete with
hydrolyzed whey protein formula and soy formula that are currently
marketed to infants with cow's milk allergy, when mother's
breastmilk is not available.

This is an interesting research finding which will likely have an
impact on future agricultural and food research work. As for
application for human consumption, it seems to have a long way to
go before this milk reaches human infant formula shelves in our
grocery stores.